In the boreal forests of Europe, a young brown bear clashes with wolves and tries to find a mate beneath the stars. On the edge of the Arctic Circle, lies an enchanted wilderness. In Europe's boreal forest, It's so far north that in winter, nights can last 20 hours. This woodland is home to a population of secretive bears that lives most of their lives in the dark. But now, using low-light cameras we can see their nighttime world as if it were day.

In the fourth episode of the series, legendary nature and cultural photographer Art Wolfe captures the great brown bear with the stunning backdrop of Alaska’s mountains and glaciers, immigrating wildebeests in the plains East Africa, and the hard-to-find gorillas of Uganda.

A bird's-eye view of some of the world's greatest natural spectacles. Amazing sights from five continents are revealed in a whole new light. Using cutting edge new filming techniques to show everything in exquisite detail, viewers have a uniquely privileged perspective. The first episode takes flight across North America, as a flock of millions of snow geese discover what it is like to be on the hit list of America's national bird: the bald eagle. In California, pelicans reveal devil rays that perform astonishing somersaults and find bizarre grunion fish that wriggle ashore to spawn. In Alaska, bald eagles swoop among brown bears fishing for salmon. And on the Great Plains, cowbirds duck and dive under the feet of fighting bison.

Earthflight departs on its grand European tour, using a host of techniques including taking extraordinary footage from microlites as they fly alongside imprinted birds. Among other wonders, cameras soar with cranes and geese over Venice, the white cliffs of Dover and Edinburgh. White storks leave Africa and struggle to reach Istanbul, the gateway to Europe, while cranes take an easier route over the monkey-guarded Rock of Gibraltar. In France, the white horses of the Camargue make a splash around the new arrivals. In Rome, the heat of the city lures 20 million starlings that perform nature's greatest aerial display to outwit peregrines. In Hungary, sand martins grab mayflies from the air; and at Bass Rock, gannets create Britain's greatest natural spectacle as they dive in exquisite slow-motion. The story takes an emotional turn as storks and swallows wait for their partners to return and indulge in a spot of DIY to impress. Finally, geese touch down in Svalbard to raise a family. To protect their young, a squadron of birds assemble to see off polar bears. With views of birds flying over the Loire Valley, London docklands and the bulb fieds of Holland, this is Europe as never before.

To our medieval forebears the world could appear mysterious, even enchanted. Sightings of green men, dog heads and alien beings were commonplace. The world itself was a book written by God. But as the Middle Ages grew to a close, it became a place to be mastered, even exploited.

Every year grizzly bear families in North America depend for their survival on a spectacular natural event: the return of hundreds of millions of salmon from the Pacific Ocean to the mountain streams where they were born. The salmon travel thousands of miles to spawn and then die. The great run not only provides food for bears, but for killer whales, wolves, bald eagles, and even the forest itself. The question is: will the salmon return in time to keep hungry bears alive?
A mother grizzly and her cubs emerge from their den high in snowy Alaskan mountains. Filming from the air the team capture a TV first, following the bears as they negotiate a near vertical slope on their journey to the coast where they await the return of the salmon. Meanwhile, the salmon are making their way to the to river mouths where they must swim upstream and against the current. The programme reveals how they tackle the torrents and leap over waterfalls, a feat equivalent to a human jumping over a house. Dozens of hungry bears eagerly await the salmon that make it up river. In another TV first, underwater cameras record the ingenuity and fancy footwork they use to collect dead salmon from the bottom of deep pools.